This invention relates to foamed liquids, and more particularly to an extruder by which foamed glue selectively is delivered to an elongated orifice assembly for extrusion onto a substrate surface, or is bypassed to a defoamer for recycling when extrusion is not taking place.
U.S. Pat. No. 4,258,088 describes the desirability of maintaining constant pressure of foamed glue at an elongated extruder orifice, whether glue is being extruded or being bypassed to a defoamer for recycling during periods when extrusion is not occurring. This is achieved in the patent by coupling the output conduit of the foamer through a control valve selectively to a foam infeed conduit leading to the extruder nozzle, or to a foam bypass conduit leading to the defoamer, and dimensioning the foam infeed conduit and nozzle assembly, on the one hand, and the bypass conduit on the other hand, to have the same resistance to flow.
Related U.S. Pat. No. 3,965,860 discloses an elongated extruder in which a plurality of longitudinally spaced nozzles are supplied from a common elongated chamber coupled to a foam infeed conduit.